# Carbon dioxide is a greenhouse gas. Explain how an increase in carbon dioxide levels in the atmosphere leads to climate change and describe two possible effects of climate change on living organisms.

> Pearson Edexcel A-Level Biology A (9BI0) — 3.3 Climate change · Explain and Describe · 5 marks

> Levels of carbon dioxide in Earth's atmosphere have been rising since the Industrial Revolution, largely due to the burning of fossil fuels and deforestation. Scientists have recorded a correlation between rising carbon dioxide concentrations and rising mean global temperatures.

## Mark scheme (5 marks)

1. Carbon dioxide (and other greenhouse gases) trap/absorb heat (infrared radiation) in the atmosphere
2. This causes mean global temperatures to rise / global warming
3. Effect 1 on living organisms — named valid effect, e.g. species / organisms may shift their distribution / range to cooler regions (poles or higher altitudes) as their original habitat becomes too warm
4. Effect 2 on living organisms — named valid effect, e.g. some species may face extinction if they cannot adapt or migrate as habitats/food sources are lost
5. Qualitative link made between rising temperatures and change in biodiversity / ecosystems, e.g. as temperatures rise, interspecific relationships (e.g. predator–prey, pollinator–plant) may become disrupted because species respond to warming at different rates

## Key terms

- [greenhouse gas](https://www.gradenine.co.uk/glossary/greenhouse-gas)
- [carbon dioxide](https://www.gradenine.co.uk/glossary/carbon-dioxide)
- [climate change](https://www.gradenine.co.uk/glossary/climate-change)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain and Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/carbon-dioxide-is-a-greenhouse-gas-3eed98dc) · Published by Druglandscape Ltd.